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A TEA LECTURE.

Tutor---Pupil.

Tut. Come—the tea is ready. Lay by your book, and let us talk a little You have assisted in tea-making a great many times, and yet I dare say you nevěr considered what kind of an operation it was.

Pup. An operation of cookery—is it not?

Tut. You may call it so; but it is properly an operation of chemistry.

Pup. Of chemistry! I thought that had been a very deep sort of a business.

Tut. 0—there are many things in common life that belong to the deepest of sciences. Making tea is the chemical operation called infusion, which is, when a hot liquor is poured upon a

substance in order to extract something from it. The water, you see, extracts from the tea-leaves their colour, taste, and flavour.

Pup. Would not cold water do the

same ?

Tut. It would, but more slowly. Heat assists almost all liquors in their power of extracting the virtues of herbs and other substances. Thus good house-wives were formerly used to boil their tea, in order to get all the goodness from it as completely as possible. The greater heat and agitation of boiling make it act more powerfully. The liquor in which a substance has been boiled is called a decoction of that substance.

Pup. Then we had a decoction of mutton at dinner to-day,

Tut. We had-broth is a decoction, and so are gruel and barley-water. But when any thing is put to steep in a cold

a

liquor, it is called maceration. The ingredients of which ink is made are macerated. In all these cases, you see, the whole substance does not mix with the liquor, but only part of it. The reason is, that part of it is soluble in the liquor, and part not.

Pup. What is the meaning of that?

Tut. Solution is when a solid put into a fluid entirely disappears in it, leaving the liquor clear. Thus when I throw this lump of sugar into my tea, you see it gradually wastes away till it is all gone, and then I can taste it in every single drop of my tea; but the tea is

l as clear as before.

Pup. Salt would do the same.

Tut. It would. But if I were to throw in a lump of chalk, it would lie undissolved at the bottom.

Pup. But it would make the water white.

Tut. True, while it was stirred; and then it would be a diffusion. But while the chalk was thus mixed with the liquor, it would lose its transparency, and not recover it again, till by standing, the chalk had all subsided, and left the liquor as it was before.

Pupil. How is the cream mixed with the tea ?

Tut. Why, that is only diffused, for it takes away the transparency of the tea. But the particles of cream being finer and lighter than those of chalk, it remains longer united with the liquor. However, in time the cream would separate too, and rise to the top, leaving the tea clear. Now, suppose you had a mixture of sugar, salt, chalk, and tea-leaves, and were to throw it into water, either hot or cold;what would be the effect ?

Pup. The sugar and salt would be dissolved and disappear. The tea-leaves would yield their colour and taste. The

chalk-I do not know what would become of that.

Tut. Why, if the mixture were stirred, the chalk would be diffused through it, and make it turbid or muddy; but on. standing, it would leave it unchanged.

Pup. Then there would remain at bottom the chalk and tea-leaves.

Tut. Yes. The clear liquor would contain in solution salt, sugar, and those particles of the téa, in which its colour and taste consisted; the remainder of the tea and the chalk would lie undissolved.

Pup. Then I suppose tea-leaves, after the tea is made, are lighter than at first.

Tut. Undoubtedly. If taken out and dried they would be found to have lost part of their weight, and the water would have gained it. Sometimes, however, it is an extremely small por'tion of a substance which is soluble, but it is that in which its most remarkable qualities reside. Thus a small